Piston ring for piston engines

ABSTRACT

The invention relates to a slot piston ring ( 1 ) for the pistons of internal combustion engines or compressors, having a peripheral recess ( 9 ) (a so-called scraper ring) that extends close to the slot ( 2 ) on the external periphery ( 3 ) of the piston facing away from the combustion chamber. The aim of the invention is to reduce oil consumption and the amount of leakage gas of such a piston. To this end, the recess is configured to extend from a zone ( 10 ) diametrically opposite the slot, starting with a maximum height ( 12 ) which gradually decreases to zero ( 13 ) in the direction of the slot or close to the slot.

CROSS REFERENCE TO RELATED APPLICATIONS

Applicant claims priority under 35 U.S.C. §119 of German Application No.100 44 241.2 filed Sep. 7, 2000. Applicant also claims priority under 35U.S.C. §365 of PCT/DE01/02644 filed Jul. 11, 2001. The internationalapplication under PCT article 21(2) was not published in English.

The invention relates to a slot piston ring for pistons for internalcombustion engines or compressors.

Such a piston ring is known from CH-PS 171 815. In connection with thepiston ring shown there, provision is made on the side facing away fromthe combustion chamber on the external peripheral surface (runningsurface) for a groove-like recess that extends fully around up to closeto the site of the slot in order to obtain a rectangular ring gap. Sucha recess for a so-called nose ring is produced by milling. Such a pistonring is not readily satisfactory with respect to lubricant consumptionand the passage of leakage gas.

Therefore, the problem of the present invention is to find a piston ringthat assures a low consumption of oil and only minor passage of leakagegas in the presence of adequate lubrication conditions, and that can bemanufactured at favorable cost.

The solution to this problem is obtained with a piston ring having arecess configured to extend from a zone diametrically opposite the slotwith a maximum height gradually decreasing to zero up to or near theslot.

Advantageous further developments according to the invention arediscussed below.

The invention is described in the following in greater detail with thehelp of exemplified embodiments shown in the drawing, in which:

FIG. 1 is a top view of the slot of a piston ring according to the priorart.

FIG. 2 is a top view of the slot of a piston ring as defined by theinvention.

FIG. 3 is a side view of a piston ring as defined by the invention, witha sectional representation of the nose-shaped recess; and

FIG. 4 is a side view of a piston ring as defined by the invention witha sectional representation of the rectangular recess.

A piston ring 1 with the slot 2 that is simultaneously acting as acompression and oil-stripping ring has a recess 4 on its external side 3facing away from the combustion chamber. In the prior art, according toFIG. 1, said recess is extending all around like a groove up to the ends5, 6 of the piston ring near the slot 2 at a uniform height 7.

In connection with a piston ring 8 as defined by the invention accordingto FIGS. 2 to 4, which is designed in the form of a nose groove ring, acorresponding recess 9 is extending starting from a zone 10diametrically opposite the slot or gap side 11 at a maximum level 12 upto the slot 2 or gap side 11, gradually decreasing to zero 13. Thecourse of the level of the recess 9 is indicated in the drawing by adotted line.

Such a recess 9 is produced on the piston ring 8 shown by a simpleturning process, in which the piston ring 8 is chucked inclined in itsreceptacle, so that the corresponding cut is produced in theconventional manner opposite the gap side 11, but decreases to zerodiametrically opposite the gap side 11.

The embodiment of the piston ring shown in FIG. 3 is different from theone shown in FIG. 4 in that the recess 9 is realized in one embodiment(FIG. 3) with a rounded shape (nose 14), and in the other embodimentwith a rectangular shape 15 (FIG. 4).

Such a nose or grooved nose ring can be employed in connection withpistons for internal combustion engines or compressors in the ringgroove one of the piston, on the one hand, and/or in the ring groove twoof the piston on the other hand. It has been found in this connectionthat as compared to conventional embodiments, it was possible todistinctly reduce the oil consumption, on the one hand, and the passageof leakage gas (blow-by) on the other hand, depending on in whichlocation it is used. Therefore, it can be noted that with such a pistonring, it is possible in a manner that is simple both in terms ofconstruction and manufacture to provide a piston ring for the piston ofan internal combustion engine or a compressor with which excellentresults are achieved with respect to the passage of leakage gas and oilconsumption in the presence of adequate lubrication conditions.

1. A slot piston ring for pistons for internal combustion engines or compressors, comprising a slot and a recess extending externally on the side facing away from the combustion chamber up to or close to the slot, said recess being part of an outer flanged portion of varying thickness, wherein diametrically opposite the slot, at a point of minimum thickness of the flanged portion, the recess has its maximum height, and wherein up to or near the slot the recess is gradually decreased to zero and the flanged portion has its maximum thickness.
 2. The slot piston ring according to claim 1, wherein the recess has a rectangular shape.
 3. The slot piston ring according to claim 1, wherein the recess has a rounded shape.
 4. The slot piston ring according to claim 1, wherein the recess is mechanically produced by a turning process. 